Stapler beam architecture

ABSTRACT

An end effector that can have an upper jaw and a lower jaw. A wrist can connect the end effector to an elongated shaft. A beam member can be arranged to translate within the upper and lower jaw. An actuation assembly can have a pushing assembly configured to transfer compressive force to the beam member and a pulling assembly configured to transfer tensile force to the beam member.

CROSS REFERENCE TO RELATED APPLICATION DATA

The present application is a U.S. National Stage Application ofPCT/US2017/050735 filed Sep. 8, 2017; which claims the benefit of U.S.Provisional Appln. No. 62/385,636 filed Sep. 9, 2016; the fulldisclosures which are incorporated herein by reference in their entiretyfor all purposes.

BACKGROUND

Minimally invasive surgical techniques are aimed at reducing the amountof extraneous tissue that is damaged during diagnostic or surgicalprocedures, thereby reducing patient recovery time, discomfort, anddeleterious side effects. As a consequence, the average length of ahospital stay for standard surgery may be shortened significantly usingminimally invasive surgical techniques. Also, patient recovery times,patient discomfort, surgical side effects, and time away from work mayalso be reduced with minimally invasive surgery.

A common form of minimally invasive surgery is endoscopy, and a commonform of endoscopy is laparoscopy, which is minimally invasive inspectionand/or surgery inside the abdominal cavity. Reloadable stapling devicescan be used in conjunction with laparoscopic surgeries. Telesurgicallycontrolled stapling devices can include servo controlled wrist jointsthat yaw and pitch at relatively large angles (e.g., up to and over 90degrees). The articulation of such wrist joints can place a large amountof strain on actuation components that extend through the wrist.

BRIEF SUMMARY

Embodiments disclosed herein relate to surgical devices having wriststhat can yaw and pitch at relatively large angles. Such wrists can havea yaw axis spatially separated from a pitch axis, with the yaw and pitchaxes being perpendicular to one another as well as to a longitudinalaxis that defines the extension of an arm or shaft of a telesurgicallycontrolled device. In some cases, the yaw and pitch angles can be up to45, 60, or 90 degrees.

In many embodiments, a flexible actuation assembly that extends througha wrist that can yaw and/or pitch at relatively large angles includes apulling assembly and a pushing assembly. The flexible actuation assemblycan be used to open and close jaws of a surgical device and/or toactuate other implements such as cutting and/or stapling devices. Inmany embodiments, the pushing element can transmit compressive forceeven while having a substantial amount of curvature induced via high yawand/or pitch angles of the wrist. In many embodiments, the pushingassembly does not transmit significant amount of tensile force and thepulling element is used to transmit tensile force for proximal movementand actuation of the surgical device. In a similar manner, the pullingcomponent may not transmit significant amount of compressive force. Inmany embodiments, the combination of the pushing assembly and thepulling assembly into the flexible actuation assembly enables use of theflexible actuation assembly for both compressive and tensile forceapplication (i.e.,) pushing and pulling) to actuate components of an endeffector of a surgical device.

The pushing assembly and the pulling component can be integrated along ashared axis with the pushing component being concentrically arrangedabout the pulling component In some embodiments, the pushing componentincludes a coiled spring and the pulling component includes a braidedcable. Alternatively the pulling component can be concentricallyarranged about the pushing component.

To enable a high degree of wrist flexibility, the wrist assembly can beconstructed from outer links that define yaw and pitch geometry for thewrist assembly. The outer links can house a flexible portion of theactuation mechanism. However, compression of the actuation mechanismwithin a wrist can cause buckling and decrease efficiency of forcetransmission. To help mitigate such issues, inner links can be providedthat connect the outer links to one another. The inner links can definea passage that constrains and limits lateral movement of the actuationmechanism, and thus mitigate buckling.

Thus, in one aspect, an apparatus is described that includes an endeffector, a beam member, a pulling assembly, and a pushing assembly. Theend effector includes an upper jaw and a lower jaw. A wrist connects theend effector to an elongated shaft. The beam member is arranged totranslate within the upper jaw and the lower jaw. The beam member has afirst portion for moveably coupling to the upper jaw and a secondportion for moveably coupling to the lower jaw. The pulling assembly isconnected to the beam member. The pulling assembly is flexibly housedwithin the wrist and applies tensile force to the beam member. Thepushing assembly is connected to the beam member. The pushing assemblyis flexibly housed within the wrist and applies compressive force to thebeam member. In many embodiments, the wrist is configured to pitch andyaw with the pulling assembly and the pushing assembly housed therein.

The pulling assembly of the apparatus can have any suitableconfiguration. For example, the pulling assembly can include anelongated cable. The pulling assembly can include a braided sheath. Thepulling assembly can include a plurality of sheet metal bands. Thebending stiffness of the pulling assembly can be the same for actuationof the wrist that pitches the end effector relative to the elongatedshaft and actuation of the wrist that yaws the end effector relative tothe elongated shaft.

The pushing assembly of the apparatus can have any suitableconfiguration. For example, the pushing assembly can include an innerlumen that surrounds the pulling assembly. The pushing assembly caninclude a close-coiled spring. The close-coiled spring can have acylindrical outer surface. The close-coiled spring can have interfacingconvex and concave surfaces. The close-coiled spring can include aspiral cut tube. The pushing assembly can include a tube having apattern of recesses that reduce bending stiffness of the tube whilemaintaining adequate axial stiffness to transmit compressive force tothe beam member. The pushing assembly can include a plurality of pushingelements that separate under tension. The pushing assembly can include aplurality of spherical members. The pulling assembly can define an innerlumen that houses the plurality of spherical members. The sphericalmembers can be linked by a flexible rod. The pushing assembly caninclude a plurality of separate elements having interfacing surfacesthat limit transverse relative sliding between the elements to onedirection. The pushing assembly can include a plurality of separateelements having interfacing surfaces that inhibit relative twistingbetween the elements. The pushing assembly can include a stack of flatwashers. The pushing assembly can include a stack of torus disks. Thepushing assembly can include a stack of rectangular washers defining alumen through which the plurality of sheet metal bands extends. Thebending stiffness of the pushing assembly can be the same for actuationof the wrist that pitches the end effector relative to the elongatedshaft and actuation of the wrist that yaws the end effector relative tothe elongated shaft.

In another aspect, a surgical tool is described that includes an endeffector, a beam member, and an actuation assembly. The end effectorincludes an upper jaw and a lower jaw. A wrist connects the end effectorto an elongated shaft. The beam member is arranged to translate withinthe upper jaw and the lower jaw. The beam member has a first portion formoveably coupling to the upper jaw and a second portion for moveablycoupling to the lower jaw. The actuation assembly includes a pushingassembly that transfers compressive force to the beam member and apulling assembly that transfers tensile force to the beam member. Inmany embodiments, the wrist is configured to pitch and yaw with theactuation assembly housed therein.

The actuation assembly of the surgical tool can have any suitableconfiguration. For example, the pulling assembly can include anelongated cable. The pulling assembly can include a braided sheath. Thepulling assembly can include a plurality of sheet metal bands. Thebending stiffness of the pulling assembly can be the same for actuationof the wrist that pitches the end effector relative to the elongatedshaft and actuation of the wrist that yaws the end effector relative tothe elongated shaft. The pushing assembly can include an inner lumenthat surrounds the pulling assembly. The pushing assembly can include aclose-coiled spring. The close-coiled spring can have a cylindricalouter surface. The close-coiled spring can have interfacing convex andconcave surfaces. The close-coiled spring can include a spiral cut tube.The pushing assembly can include a tube having a pattern of recessesthat reduce bending stiffness of the tube while maintaining adequateaxial stiffness to transmit compressive force to the beam member. Thepushing assembly can include a plurality of pushing elements thatseparate under tension. The pushing assembly can include a plurality ofspherical members. The pulling assembly can define an inner lumen thathouses the plurality of spherical members. The spherical members can belinked by a flexible rod. The pushing assembly can include a pluralityof separate elements having interfacing surfaces that limit transverserelative sliding between the elements to one direction. The pushingassembly can include a plurality of separate elements having interfacingsurfaces that inhibit relative twisting between the elements. Thepushing assembly can include a stack of flat washers. The pushingassembly can include a stack of torus disks. The pushing assembly caninclude a stack of rectangular washers defining a lumen through whichthe plurality of sheet metal bands extends. The bending stiffness of thepushing assembly can be the same for actuation; of the wrist thatpitches the end effector relative to the elongated shaft and actuationof the wrist that yaws the end effector relative to the elongated shaft.A one-dimensional array of flexible rods can be used as both the pullingassembly and the pushing assembly. A nickel-titanium rod can be used asboth the pulling assembly and the pushing assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-6 show views of a surgical tool, in accordance with someembodiments.

FIGS. 7 and 8 show cross-sectional views of the surgical tool of FIGS.1-6.

FIG. 9 shows an embodiment of an actuation assembly of the surgical toolof FIGS. 1-6, in accordance with some embodiments.

FIG. 10 shows a cross-sectional view of the actuation assembly of FIG.9.

FIG. 11 shows a cross-sectional view of a distal portion of theactuation assembly of FIG. 9.

FIG. 12 shows a cross-sectional view of a proximal portion of theactuation assembly of FIG. 9.

FIGS. 13 and 14 show an embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIGS. 15 and 16 show another embodiment of a pushing assembly of anactuation assembly of the surgical tool of FIGS. 1-6.

FIG. 17 shows an embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIG. 18 shows another embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIG. 19 shows another embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIG. 20 shows a view of another embodiment of an actuation assembly ofthe surgical tool of FIGS. 1-6.

FIGS. 21 and 22 show another embodiment of a pushing assembly of anactuation assembly of the surgical tool of FIGS. 1-6.

FIG. 23 shows another embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIG. 24 shows a cross-sectional view of the pushing assembly of FIG. 23.

FIG. 25 shows another embodiment of a pushing assembly of an actuationassembly of the surgical tool of FIGS. 1-6.

FIG. 26 shows views of an individual element of the pushing assembly ofFIG. 25.

FIG. 27 shows a cross sectional view of another embodiment of anactuation assembly of the surgical tool of FIGS. 1-6.

FIGS. 28 and 29 show top views of a portion of the actuation assembly ofFIG. 27 located at a wrist of the surgical tool.

FIG. 30 shows another embodiment of an actuation assembly of thesurgical tool of FIGS. 1-6.

FIGS. 31 and 32 show views of another embodiment of anactuation assemblyof the surgical tool of FIGS. 1-6.

FIG. 33 shows another embodiment of an actuation assembly of thesurgical tool of FIGS. 1-6.

FIG. 34 shows a cross-sectional view of another embodiment of anactuation assembly of the surgical tool of FIGS. 1-6.

FIG. 35 shows a view of a wrist assembly of the surgical tool of FIGS.1-6.

FIG. 36 shows a cross-sectional view of the wrist assembly of FIG. 35.

FIG. 37 shows a perspective view of an outer link assembly, according tosome embodiments of the invention.

FIGS. 38-40 show a method of assembling a wrist assembly, according tosome embodiments of the invention.

DETAILED DESCRIPTION

In the following description, various embodiments will be described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will also be apparent to one skilled in the art that theembodiments may be practiced without the specific details. Furthermore,well-known features may be omitted or simplified in order not to obscurethe embodiment being described.

FIGS. 1-3 show a surgical tool 10 that includes a proximal chassis 12,an instrument shaft 14, and a distal end effector 16 having an upper jaw18 that can be articulated to grip a patient tissue. The proximalchassis 12 includes input couplers 22 that may interface with and bedriven by corresponding output couplers of a telesurgical surgerysystem, such as the system disclosed within Pub. No. US 2014/01.83244Al, which is incorporated by reference herein. The input couplers 22 aredrivingly coupled with one or more input members that are disposedwithin the instrument shaft 14. The input members are drivingly coupledwith the end effector 16. As shown at FIGS. 2 and 3, input couplers 22of the proximal chassis 12 can be adapted to mate with various types ofmotor packs 13, such as stapler specific motor packs disclosed at U.S.Pat. No. 8,912,746, or the universal motor packs disclosed at U.S. Pat.No. 8,529,582, which are incorporated by reference herein.

FIGS. 4-6 show perspective, side, and top views of a distal end of thesurgical tool 10 including the end effector 16. End effector 16 ismoveably connected to the instrument shaft 14 by a wrist assembly 24.The wrist assembly 24 has at least two degree of freedom and providesfor attachment of the end effector 16 to the elongated instrument shaft14 for articulation of the end effector 16 about two orthogonal axesrelative to the instrument shaft 14. The wrist assembly 24 is configuredto yaw the end effector 16 relative to the instrument shaft 14 about anaxis 2, which is perpendicular to axis 1 that the instrument shaft 14extends along. The wrist assembly 24 is also configured to pitch the endeffector 16 relative to the instrument shaft 14 about an axis 3, whichis perpendicular to axis 1 and axis 2. As shown, the yaw axis 2 isproximal (farther from the end effector 16) to the pitch axis 3, howeverthis is not a requirement and in some embodiments the yaw axis 2 isdistal to the pitch axis 3.

FIGS. 7 and 8 are a cross-sectional views showing details of endeffector 16 that include the upper jaw 18 and a lower jaw 26. The lowerjaw 26 can be configured to accommodate and support a removable ornon-removable stapling cartridge. The upper) jaw 18 is pivotally coupledwith the lower jaw 26 to articulate relative to the lower jaw 26 toclamp tissue. A beam member 28 is driven from a proximal state shown atFIG. 7 to a distal state shown at FIG. 8 to actuate the upper jaw 18.Movement of the beam member 28 can serve to forcibly secure the upperjaw 18 over tissue with respect to the lower jaw 26. Optionally, thebeam member 28 can also allow for cutting tissue and deploying staplesfrom the cartridge into the cut tissue.

The beam member 28 includes an upper beam portion 30 that is configuredto slide within a rail feature 32 of the upper jaw 18. The rail feature32 includes a ramp 34 for the upper beam portion 30 to engage from aproximal most garage area 36. The open position shown at FIG. 7 can bemaintained by a resilient device, such as a spring, or opened and)closed by a secondary mechanism (not shown). Partial closure of theupper jaw 18 can be affected by distal movement of the upper beamportion 30 onto the ramp 34. Complete closure of the upper jaw 18 isachieved when the upper beam portion 30 is moved distally past the ramp34 and onto the rail feature 32. Proximal movement of the upper beamportion 30 off of the ramp 34 removes the closure force applied to theupper jaw 18 by the beam member 28. A resilient device or secondarymechanism can then cause a closed or partially closed upper jaw 18 toopen. Thus, back and forth movement of the upper beam portion 30 alongthe ramp 34 can toggle the end effector 16 open and closed.

The beam member 28 also includes a lower beam portion 38 that configuredto slide within a rail feature of the lower jaw 18. The lower beamportion 38 can actuate a sled (such as disclosed in Pub. No. US2014/0183244 A1) configured for ejecting staples out the lower jaw 26during distal movement of the beam member 28. Alternatively, the lowerbeam portion 38 can be integrated with such a sled.

FIG. 9 shows a view of the beam member 28. Here, the upper beam portion30 includes an integrated cutting member 40 that is configured to cuttissue. However, in other embodiments a tissue cutting device can beseparate from the beam member 28 or implemented into the beam member 28in a different manner. The upper beam portion 30 includes an upperflange 42, which transversely extends from the integrated cutting member40. The upper flange 42 is configured to directly interface with therail feature 32 and the ramp 34. In a similar manner a lower flange 44is provided to slide with a rail feature of the lower jaw 26. Anelongated actuation assembly 46 is attached to the beam member 28 forproviding distal and proximal movement to the beam member 28.

FIGS. 10-12 show cross-sectional views of the beam member 28 and theactuation assembly 46. The actuation assembly 46 includes a pushingassembly 48 and a pulling assembly 50. In the embodiment shown, thepushing assembly 48 is configured as a close-coiled spring and isadapted to transmit compressive force from a drive rod 52 to the beammember 28. The pushing assembly 48 can be externally constrained by asheath 54, which can be constructed from any suitable material such as,for example, a lubricous polymer material such as PTFE. The coileddesign of the pushing assembly 48 allows compressive force to betranslated effectively to the beam member 28 to push the beam member 28in the distal direction. The pushing assembly 48 can be constructed inany suitable manner. For example, in some embodiments the pushingassembly 48 is constructed from a coiled wire. In some embodiments, thepushing member 48 is spirally cut from a tube. In some cases, thecompressive elements (e.g., coils) of the pushing assembly will separateunder tension, and thus in such cases the pushing assembly may beemployed primarily to transfer compressive force.

The pulling assembly 50 can be constructed from any suitable element orelements capable of reacting tensile load (e.g., a braided cable or aflexible rod). In the embodiment shown, the pulling assembly 50 isretained within the beam member 28 by a crimp portion 56. In some cases,the pulling assembly 50 may be relatively ineffective to transfercompressive force from the drive rod 52 to the beam member 28 as it mayhave the tendency to collapse or buckle on itself, and thus in suchcases the pulling assembly 50 may be employed primarily to transfertensile force. The pulling assembly 50 is adapted to transmit tensionforce applied by the drive rod 52 to the beam member 28. The drive rod52 is located within the instrument shaft 14 and is drivingly coupled toone or more of the input couplers 22 shown at FIG. 1. The pullingassembly 50 allows tensile force to be transmitted effectively from thedrive rod 52 to the beam member 28, to pull the beam member 28 in theproximal direction. The pushing assembly 48 and pulling assembly 50operate in a complementary manner to provide distal and proximal motionto the beam member 28 by transmitting tensile force via the pullingassembly 50 and compressive force via the pushing assembly 48.Transmitting tensile force via the pulling assembly 50 and compressiveforce via the pushing assembly 48 enables a very flexible and compactdesign for the actuation assembly 46, characteristics that enable theactuation assembly 46 to translate within the wrist 24, which can bedisposed at relatively large yaw and pitch angles during operation.

The pushing assembly 48 can have a cylindrical outer diameter to providea substantially continuous outer profile and larger/stiffer wire sectionfor given fixed inner and outer diameters. For example, FIGS. 13 and 14show a pushing assembly 48 a that has a cylindrical outer surface 48aos. Any suitable approach can be used to fabricate the pushing assembly48 a, such as grinding a coil spring to form the cylindrical outersurface 48 aos.

The pushing assembly 48 can include a close-coil spring havinginterfacing convex/concave surfaces. For example, FIGS. 15 and 16 show apushing assembly 48 b that has interfacing convex/concave surfaces thatnest together with adjacent sections of the coil to increasedistribution contact stresses and improve column stability relative to around wire coil spring.

The pushing assembly 48 is not limited to a close-coiled spring designillustrated in FIGS. 10-16. For example, FIG. 17-19 show flexiblepushing assembly 48 c, 48 d, 48 e that can be formed from a solid tubeby locally cutting a pattern into the solid tube in the vicinity of thewrist 24 to increase bending flexibility of the pushing assembly at thewrist 24 without materially decreasing compressive stiffness. Thepushing assembly 48 c, 48 d, 48 e can be formed by laser cutting apattern into a tube made from any suitable material (e.g., a suitablemetal, a suitable polymer based material). In the pushing assembly 48 cshown in FIG. 17, the pattern enhances flexibility where gaps are formedin the tube and retains axial stiffness where material is left in place.The pushing assembly 48 d shown in FIG. 18 has a plurality ofcircumferential slits arranged in a spiraling pattern. In the pushingassembly 48 e shown in FIG. 19, the pattern forms separate interlockingsegments that provide flexibility while inhibiting relative dislocationof the interlocking segments.

The pushing assembly 48 can be formed from any suitable configuration ofseparate interfacing segments. For example, FIG. 20 shows a pushingassembly 48 f that is made from a stack of flat washers. FIG. 21 andFIG. 22 show a pushing assembly 48 g that is made from a stack of torusdisks. FIG. 23 and FIG. 24 show a pushing assembly 48 h that is madefrom a stack of conical washers. Each of the conical washers hasnon-planar interfacing surfaces (e.g., spherical interfacing surfaces)that interact to inhibit relative transverse movement of the conicalwashers to enhance alignment of the conical washers with the pullingassembly 50, which extends through centers of the conical washers. As aresult of the shape of the conical washers, the pushing assembly 48 haccommodates bending of the pushing assembly 48 h in any directiontransverse to the local axial direction of the actuation assembly 46 viarelative sliding in any direction between adjacent conical washers.

The pushing assembly 48 can be formed from a stack of any suitablenon-axially-symmetric interfacing segments. For example, FIG. 25 shows apushing assembly 48 i that is made from a stack of separatenon-axially-symmetric members 70. FIG. 26 shows different views of oneof the members 70. In the embodiment shown, the member 70 has atransversely oriented protruding region 72 and a transversely orientedrecessed region 74 shaped to accommodate and interface with theprotruding region 72 of the adjacent member 70. The protruding region 72and the recessed region 74 are shaped to limit relative sliding betweenadjacent members 70 to the direction in which the regions 72, 74 extendtransverse to the local extending direction of the pushing assembly 48i. The interfacing regions 72, 74 also serve to inhibit relativetwisting between adjacent members 70 around the local extendingdirection of the pushing assembly 48 i, thereby inhibiting twisting ofthe pushing assembly 48 i between the proximal and distal end of thepushing assembly 48 i.

The actuation assembly 46 can include a stack of elongated sheet metalstrips. For example, FIG. 27 shows a cross sectional view of anactuation assembly 46 j of the surgical tool of FIGS. 1-6. The actuationassembly 46 j includes elongated sheet metal strips 76 that areconfigured to react both compressive and tension loads whileaccommodating flexure of the actuation assembly 46 j transverse to theplane of the sheet metal strips 76 as well as twisting of the actuationassembly 46 j along the length of the actuation assembly 46 j. Theactuation assembly 46 j includes an outer sheath 78 having a rectangularchannel 80 through which the sheet metal strips 76 extend from theproximal end of the actuation assembly 46 j to the distal end of theactuation assembly 46 j. The outer sheath 78 constrains the stack ofsheet metal strips 76 so as to prevent transverse buckling of the sheetmetal strips 76 when the sheet metal strips are loaded in compressionduring distal advancement of the beam member 28. FIG. 28 illustratestwisting of the actuation assembly 46 j and the associated twisting ofthe sheet metal strips 76 that may be induced in response to rotation ofthe end effector 16 relative to the instrument shaft 14. FIG. 29illustrates flexure of the sheet metal strips 76 in the vicinity of thewrist assembly 24 that can be induced in response to reorientation ofthe end effector 16 relative to the instrument shaft 14.

The actuation assembly 46 can include a stack of elongated sheet metalbands to transmit tension load between the drive rod 52 and the beammember 28 and a stack of rectangular washers to transmit compressionload between the drive rod 52 and the beam member 28. For example, FIG.30 shows a isometric view of a actuation assembly 46 k that includes astack of sheet metal strips 76 that are attached to and extend betweenthe drive rod 52 and the beam member 28. In the actuation assembly 46 k,the sheet metal strips 76 transmit tension load from the drive rod 52 tothe beam member 28 during proximal retraction of the beam member 28. Theactuation assembly 46 k further includes a stack of rectangular washers82 that transmit compression load from the drive rod 52 to the beammember 28 during distal advancement of the beam member 28. The actuationassembly 46 k further includes an inner sheath 84 having a lumen thataccommodates the rectangular washers 82 and an outer sheath 86 having alumen that accommodates the inner sheath 84. In the embodiment shown,the outer sheath 86 has a series of recesses 88 in the vicinity of thewrist assembly 24 to increase the flexibility of the outer sheath 86 tobend transverse to the plane of the sheet metal strips 76 in response toreorientation of the end effector 16 relative to the instrument shaft 14via the wrist 24.

The actuation assembly 46 can include a plurality of flexible actuationrods. For example, FIG. 31 shows a side view of a distal portion of aactuation assembly 46 m of the surgical tool of the surgical tool ofFIGS. 1-6. The actuation assembly 46 m includes three flexible actuationrods 90 that are adapted to transmit both tension force from the driverod 52 to the beam member 28 m and compression force from the drive rod52 to the beam member 28 m. The three flexible actuation rods 90 arealigned in a common plane thereby accommodating flexure of the actuationrods 90 transverse to the common plane. The three flexible actuationrods 90 are separately routed between the drive rod 52 and the beammember 28 m, thereby accommodating twisting of the actuation rods 90that may be induced in response to rotation of the end effector 16relative to the instrument shaft 14. FIG. 32 shows an end view of thebeam member 28 m of the actuation assembly 46 g that illustratesapertures 92 in the beam member 28 m via which the actuation rods 90 arecoupled to the beam member 28 m.

The actuation assembly 46 can employ an element in place of the pullingassembly 50 that transmits both compression and tension loads from thedrive rod 52 to the beam member 28. For example, FIG. 33 shows aactuation assembly 46 n that includes a Nitinol wire 50 a in place ofthe pulling assembly 50. The Nitinol wire 50 a transmits bothcompressive and tensile loads from the drive rod 52 to the beam member28 to both distally advance and proximally retract the beam member 28.In the illustrated embodiment, the actuation assembly 46 n includes aspring 48 n, which can be a closed coil spring but does not have to be.The spring 48 n can be configured to share transmission of compressiveload from the drive rod 52 to the beam member 28 with the Nitinol wire50 a during distal advancement of the beam member 28. The spring 48 ncan also be configured to not share transmission of compressive loadfrom the drive rod 52 to the beam member 28 with the Nitinol wire 50aduring distal advancement of the beam member 28. In many embodiments,the primary function of the spring 48 n is to provide radially supportto the Nitinol wire 50 a so that the Nitinol wire can have a diameterconsistent with the diameter of the drive rod 52. Any suitable approachcan be used to attach the Nitinol wire 50 a with each of the beam member28 and the drive rod 52 such as, for example, swaging soldering,welding, etc.

In some embodiments of the actuation assembly 46, the pushing member 48is disposed within a lumen of the pulling member 50. For example, FIG.34 shows an actuation assembly 46 o including a pushing assembly 48 oand a pulling assembly 50 o having a lumen in which the pushing assembly48 o is disposed. The configuration of the actuation assembly 46 odiffers from other embodiments described herein in which the pushingassembly 48 concentrically surrounds the pulling assembly 50. In theactuation assembly 46 o, the pulling assembly 50 o comprises a sheath(e.g., a braided sheath) that encapsulates the pushing assembly 480. Thepushing assembly 48 o includes a plurality of spherical members (e.g.,ball bearings) joined by a flexible rod 66. Both the pushing assembly 48o and pulling assembly 50 o are actuated by the drive rod 52, which isdrivingly coupled to one or more of the input couplers 22 shown at FIG.1.

FIGS. 35 and 36 show perspective and cross-sectional views of the wristassembly 24. The wrist assembly 24 includes a proximal outer link 100, amiddle outer link 102, and a distal outer link 104. These three linksdetermine the kinematic pitch and yaw motion of the wrist assembly 24.As shown, the interface between the proximal outer link 100 and themiddle outer link 102 determine yaw movement of the wrist assembly 24.And the interface between the outer distal link 104 and the middle outerlink 102 determine pitch movement of the wrist assembly 24. However, inan alternative wrist configuration, this relationship can be reversedsuch that the wrist assembly 24 pitches between the proximal outer link100 and the middle outer link 102 and yaws between the distal outer link100 and the middle outer link 102 (e.g., by rotating the end effector 16relative to wrist assembly 24 by 90 degrees).

Cable portions 106 tension the wrist assembly 24 and actuate to impartmotion to the wrist assembly. In one embodiment, cable portions 106 canbe individually secured to a portion of the distal outer link 104. In anfunctionally equivalent alternate embodiment, as shown at FIG. 35, cableportions 106 are looped about a portion of the distal outer link 104.Looping cable portions 106 to the distal outer link 104 secures thecable portions 106 to the distal outer link 104 and prevents the cableportions 106 from slipping. In either embodiment, tension is applied toindividual cable portions 106 to be pulled to articulate the wrist.Differential forces applied to the cable portions 106 can actuate thewrist assembly to pitch and yaw at various angles. The cable portions106 can be drivingly coupled to one or more of the input couplers 22shown at FIG. 1. The wrist assembly also includes proximal inner link108 and distal inner link 110, which are discussed in detail below.

With attention to FIG. 37, an exemplary embodiment of a joint 112 isshown that is representative of the interfaces between the outer linksshown at FIGS. 53 and 36. The joint 112 includes a first link 114 and asecond link 116. First link 114 may include teeth 116, 118 and a bearingprojection 122. Disc 720 may include pins 124, 126, 128 and a bearingprojection 130. According to an exemplary embodiment, projections 122,130 of first and second links 114, 116 may include passages to permitcable portions 106 to pass through. Because bearing projections 122, 130are located at an outboard location relative to central apertures 134,136 cable portions 106 extending through passages adjacent to bearingprojections 122, 130 also are located at an outboard location. Thisallows for routing of other mechanisms through the central apertures134, 136. Actuation kinematics between the links are determined by theshape of the pins and teeth, which engage and disengage during movement.The bearing projections 122, 130 included curved surfaces which engageat some point throughout all angular motion to help reduce compressivestrain to the pins and teeth.

Due to the enhanced range of motion provided by joint 112, a wristincluding joint 112 may provide a desired amount of motion, such as+/−90 degrees in a pitch or yaw direction, in amore efficient mannerwith fewer parts. In previous wrist structures in which each joint islimited to a maximum roll angle of about 45 degrees, several such jointsin series are needed to relatively large roll angle for the entire wristmechanism. And as illustrated, a single joint can provide up to a 90degree roll angle limit. As a result, a manufacturing cost andcomplexity for a wrist that includes one or more joints 112 may bereduced while still achieving desired control over articulation. Inaddition, the plurality of teeth and corresponding plurality of pinsincluded in links 114,116 of joint 112 can provide enhanced timing toassist with accurately positioning links 114,116, including, forexample, returning discs to a neutral position (e.g., zero angle rollalignment), and to enhance smoothness of the motion between links114,116, such as when links 114,116 are rotated in direction relative toone another. According to an exemplary embodiment, a wrist may include aplurality of joints 112 to achieve higher ranges of motion (up to rolllimit angles), such as, for example, wrists having a range of motion ofup to +/−180 degrees in a pitch or yaw direction. Additional details ofjoint 112, and other joints usable with the embodiments disclosedherein, are disclosed in Intl. Pub. No. WO 2015/127250, which isincorporated by reference herein.

As shown at FIG. 36, the proximal and distal inner links 108,110 arespatially separated along axis 1 and offset 90 degrees from one another.Hence, the proximal internal link 108 is only partially shown. Radialsurfaces of the proximal and distal inner links 108,110 includeprotrusions (e.g. configured as clevis pins 140). The clevis pinsconnect between indentations (e.g. configured as clevis joints 142) atmedial surfaces of the external links. The clevis pins and joints 140,142 set the distances between the joints of the outer links, butotherwise are passive and do not alter joint kinematics of the outerlinks, which is determined by the tooth and pin geometry. Each side ofthe proximal and distal inner links 108,110 includes a pair of commonlyaligned clevis pins for each connection to an outer link for a total offour clevis pins per inner link 108,110. Each pair of clevis pins 140 isseparated to provide an internal passage 144 for the actuation assembly46.

An additional internal sheath 146 can be used to further support theactuation assembly 46. The actuation assembly 46 slides axially withinthe internal sheath 146. The internal sheath 146 is fixed to a distalend portion of the wrist assembly 24 and is flexible to bend withmovement of the wrist assembly 24 but does not move axially. Theinternal sheath 146 and internal passage 144 provided by the inner linksserve to guide and constrain the actuation assembly 46 during axialmovement. Internal sheath 146 and inner passage 144 prevent theactuation assembly from buckling under compressive loading (i.e. distalmovement while cutting and stapling). Prior wrist designs, such asdisclosed in the aforementioned Int'l. Pub. No. WO 2015/127250, rely ontensioned cables to maintain the outer links in position. Here, thatwould be unsatisfactory because when the actuation assembly 46 moves ina distal direction the resulting compressive force may induce slack inthe cables. The clevis pins 140 of the inner links 108,110, however,advantageously maintain the outer links in position when the actuationassembly 46 moves in a distal direction, therefore maintaining thestructure of the wrist assembly 24.

Each inner link can have a two-piece construction as depicted at FIGS.38 through 40, which also depict a technique for assembling the innerlinks to the outer links. At FIG. 38 first link portion 108 a and secondlink portion 108 b of the proximal inner link 108 are positioned toplace clevis pins 140 into clevis joints 142 of the middle outer link102. The first link portion 108 a and second link portion 108 b areinserted at angles such that gear teeth 148 of each portion intermesh tocause alignment of the portions into the formation shown at FIG. 39. Thegear teeth 148 are an assembly aid that eliminates the need for pins orother fasteners, and are not used for movement beyond assembly. However,in some embodiments, fasteners can be used in lieu of the gear teeth.After the link portions 108 a, 108 b are assembled into a complete innerproximal link 108, the proximal outer link 100 is assembled onto theremaining exposed clevis pins 140 into the formation shown at FIG. 40.In one embodiment, as shown at FIG. 40, proximal outer link 100 is alsoof two-piece construction.

Other variations are within the spirit of the present invention. Thevarious aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments associated with operationof telesurgical tools can be implemented by software, hardware or acombination of hardware and software. Thus, while the invention issusceptible to various modifications and alternative constructions,certain illustrated embodiments thereof are shown in the drawings andhave been described above in detail. It should be understood, however,that there is no intention to limit the invention to the specific formor forms disclosed, but on the contrary, the intention is to cover allmodifications, alternative constructions, and equivalents falling withinthe spirit and scope of the invention, as defined in the appendedclaims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. An apparatus comprising: an end effectorcomprising an upper jaw and a lower jaw; an instrument shaft; a wristassembly moveably connecting the end effector to the instrument shaft,wherein the wrist assembly is operable to articulate the end effectorrelative to the instrument shaft about two orthogonal axes relative tothe instrument shaft, wherein the wrist assembly comprises an internalsheath having an inner passage, and wherein the internal sheath isflexible to bend with movement of the wrist assembly but does not moveaxially; a beam member arranged to translate within the upper jaw andthe lower jaw, the beam member having a first portion for moveablycoupling to the upper jaw and a second portion for moveably coupling tothe lower jaw; and an actuation assembly comprising a pushing assemblyand a pulling assembly, wherein the pulling assembly is configured totransfer tensile force to the beam member to translate the beam memberproximally relative to the upper jaw and the lower jaw, wherein thepushing assembly is configured to transfer compressive force to the beammember to translate the beam member distally relative to the upper jawand the lower jaw, wherein the actuation assembly extends through theinner passage, and wherein the internal sheath guides and constrains theactuation assembly during movement of the actuation assembly relative tothe internal sheath.
 2. A surgical tool comprising: an end effectorcomprising an upper jaw and a lower jaw; an instrument shaft; a wristassembly moveably connecting the end effector to the instrument shaft,wherein the wrist assembly is operable to articulate the end effectorrelative to the instrument shaft about two orthogonal axes relative tothe instrument shaft, wherein the wrist assembly comprises an internalsheath having an inner passage, and wherein the internal sheath isflexible to bend with movement of the wrist assembly but does not moveaxially; a beam member arranged to translate within the upper jaw andthe lower jaw, the beam member having a first portion for moveablycoupling to the upper jaw and a second portion for moveably coupling tothe lower jaw; and an actuation assembly comprising a pushing assemblyand a pulling assembly, wherein the pulling assembly is configured totransfer a tensile force to the beam member to translate the beam memberproximally relative to the upper jaw and the lower jaw, wherein thepushing assembly is configured to transfer a compressive force to thebeam member to translate the beam member distally relative to the upperjaw and the lower jaw, wherein the actuation assembly extends throughthe inner passage, and wherein the internal sheath guides and constrainsthe actuation assembly during movement of the actuation assemblyrelative to the internal sheath.
 3. The surgical tool of claim 2,wherein: the pulling assembly comprises an elongated cable; and thepushing assembly comprises an inner lumen surrounding the elongatedcable.
 4. The surgical tool of claim 2, wherein the pushing assemblycomprises a close-coiled spring.
 5. The surgical tool of claim 4,wherein the close-coiled spring has a cylindrical outer surface.
 6. Thesurgical tool of claim 4, wherein the close-coiled spring hasinterfacing convex and concave surfaces.
 7. The surgical tool of claim4, wherein close-coiled spring comprises a spiral cut tube.
 8. Thesurgical tool of claim 2, wherein the pushing assembly comprises a tubehaving a pattern of recesses.
 9. The surgical tool of claim 2, whereinthe pushing assembly comprises a plurality of pushing elements thatseparate under tension.
 10. The surgical tool of claim 9, wherein thepushing assembly comprises a plurality of spherical members.
 11. Thesurgical tool of claim 10, wherein the pulling assembly defines an innerlumen that houses the spherical members.
 12. The surgical tool of claim11, wherein the spherical members are linked by a flexible rod.
 13. Thesurgical tool of claim 2, wherein the pushing assembly comprisesseparate elements having interfacing surfaces that limit transverserelative sliding between the separate elements to one direction.
 14. Thesurgical tool of claim 2, wherein the pushing assembly comprisesseparate elements having interfacing surfaces that inhibit relativetwisting between the separate elements.
 15. The surgical tool of claim2, wherein the pushing assembly comprises a stack of flat washers. 16.The surgical tool of claim 2, wherein the pushing assembly comprises astack of torus disks.
 17. The surgical tool of claim 2, wherein thepulling assembly comprises a plurality of sheet metal bands.
 18. Thesurgical tool of claim 17, wherein the pushing assembly comprises astack of rectangular washers defining a lumen through which theplurality of sheet metal bands extends.
 19. The surgical tool of claim2, wherein: the pushing assembly comprises a one-dimensional array offlexible rods; the pulling assembly comprises the one-dimensional arrayof flexible rods; the one-dimensional array of flexible rods transfersthe tensile force to the beam member; and the one-dimensional array offlexible rods transfers the compressive force to the beam member. 20.The surgical tool of claim 2, wherein: the pushing assembly comprises anickel-titanium rod; the pulling assembly comprises the nickel-titaniumrod; the nickel-titanium rod transfers the tensile force to the beammember; and the nickel-titanium rod transfers the compressive force tothe beam member.